1. Field of the Invention
The invention relates to a receiver cassette for web material, in particular for an exposed film web material derived from an optical flying-spot scanning device.
2. Brief Description of the Background of the Invention Including Prior Art
It is known to construct an optical flying-spot scanning device in photo composition apparatus for a photo-sensitive web material such that the web material can be fed from a transmitter feed cassette, disposed in the first cassette receiver space, to an exposure section, wherein an efferent delivery roller pair for the transport of the web material through the exposure section is disposed in transport direction of the web material behind the exposure section. A further cassette receiver space for receiver cassettes is furnished behind the efferent transfer roller pair and the insertion roller pairs and the delivery roller pairs of the optical flying-spot scanning device are subdivided in their longitudinal direction into several differently drivable or, respectively, idling sections, as taught in the German Patent document DE-C2-33 18 311.
Receiver cassettes for web material are in this case constructed such that a winding up corresponding to the advance speed of the transport system is performed in the flying-spot scanning device based on the self tension and/or internal stress of the web material. Such optical flying-spot scanning devices offer in addition the possibility to transfer the drive motion for the web material synchronous onto another apparatus through gear wheel drives.
The winding up without hub of a wheel is in addition known from the German Democratic Republic Patent document DD-PS 0 154 852. A system of a flat-lying web material is provided according to the U.S. Pat. No. 4,299,458, wherein the web material is wound within a receiver cassette onto a hub of a coil. This hub of a coil however comprises a drum and several press-on rollers distributed over the circumference of the drum such that, upon rotation of the drum and while the press-on rollers remain still standing, there is performed a winding up of the web material. It has to be considered in this context that the press-on rollers are resting on the side of the web material which is not covered with the photo-sensitive layer. Therefore, it is in general assumed that in case of a web material, which essentially comprises an illuminated and exposed film web, the exposed side then forms the inner side surface of the web material.
The deficiency of only a short web length being able to store in the receiver cassette is common to all previously known solutions such that the capacity or, respectively, the use of the capacity upstream disposed flying-spot scanning devices has to remain small. Simultaneously, the use of exposure material relatively rises when the productivity capacity is low, because substantial lengths of the web material are used up while still unexposed. The known receiver cassettes therefore have only a small receiving capacity, they are expensive to operate and they are subjected to a high use of material to be exposed.